We are getting close my friends!

The code below stores and tells us the position of the retarder handle and it works perfect!

Connect the Retarder to an Arduino Leonardo:

Retarder PIN 2 to 5v

Retarder PIN 6 to gnd

Retarder PIN 7 to A0

int analogPin= 0;
int raw= 0;
int Vin= 5;
float Vout= 0;
float R1= 10000;
float R2= 0;
float buffer= 0;

void setup()
{
Serial.begin(9600);
}

void loop()
{
byte handlePos;
int val = analogRead(0);
  if(val < 187)
    {
      handlePos = 0;
      Serial.println("handlePos = 0");
      Serial.println(val);
    }
    else if(val < 350)
    {
      handlePos = 1;
      Serial.println("handlePos = 1");
      Serial.println(val);
    } 
    else if(val < 518)
    {
      handlePos = 2;
      Serial.println("handlePos = 2");
      Serial.println(val);
    }
    else if(val < 679)
    {
      handlePos = 3;
      Serial.println("handlePos = 3");
      Serial.println(val);
    }
    else if(val < 861)
    {
      handlePos = 4;
      Serial.println("handlePos = 4");
      Serial.println(val);
    } 
    else if(val < 1024)
    {
      handlePos = 5;
      Serial.println("handlePos = 5");
      Serial.println(val);
    }
    else
    {
    Serial.println("handlePos unknown");
    Serial.println(val);
    } 
    delay(500);
}   
// by Jeroen van der Velden
// https://hackaday.io/project/8448-real-dashboard-truck-simulator
//

Download link to Arduino IDE file

Next and final challenge: send keyboard commands "+" and "-" (retarder "up" and retarder "down")